Fitting, crane hook, and crane hook assembly

ABSTRACT

A method of lifting an aircraft at a lifting location, the method comprising: securing a fitting ( 10 ) to the aircraft when the aircraft is at the lifting location; engaging the fitting with a crane hook ( 100 ); transmitting lifting load from the crane hook to the aircraft via the fitting; and removing the fitting from the aircraft. A fitting ( 10 ) for transmitting lifting loads from a crane hook ( 100 ) to an item, the fitting comprising: an attachment member ( 11 ) configured to be secured to the item; and a lifting member ( 12 ) which is pivotally coupled to the attachment member and configured to be engaged by the crane hook ( 100 ) so as to transmit lifting loads from the crane hook to the item. A crane hook ( 100 ) with a ball-and-socket connection is provided. The crane hook has an attachment link ( 106 ) having a first pivot point ( 107 ) attached to the hook forward of its centre of gravity, and a second pivot point ( 109 ) configured to be lifted by a crane, —and a biasing system which applies a biasing force to the attachment link causing the attachment link to rotate about the first pivot-point whereby the second pivot point moves towards the rear of the hook when the hook is unloaded.

FIELD OF THE INVENTION

The invention provides a fitting, crane hook and crane hook assemblywhich are particularly suitable for lifting an aircraft, but may also beused to lift other loads. The invention also relates to a method oflifting an aircraft.

BACKGROUND OF THE INVENTION

Crane recovery of an aircraft is a preferred method for many airports.However some aircraft do not have a strong point which is bothaccessible from above, and is suitably configured to attach a liftingsling or crane hook.

One solution to this problem is to inflate an airbag under a wing of theaircraft. However for large aircraft this may cause instabilityconcerns, particularly if the airbag is wet. Also the tendency of thewing to bend as the lifting occurs increases the total height of theairbag lift required, thereby exacerbating the problem.

SUMMARY OF THE INVENTION

A first aspect of the invention provides apparatus for lifting anaircraft at a lifting location, the apparatus comprising:

-   -   a fitting configured to be secured to the aircraft when the        aircraft is at the lifting location; and    -   a crane hook configured to engage the fitting and transmit        lifting load to the aircraft via the fitting.

The first aspect of the invention also provides a method of lifting anaircraft at a lifting location, the method comprising:

-   -   securing a fitting to the aircraft when the aircraft is at the        lifting location;    -   engaging the fitting with a crane hook;    -   transmitting lifting load from the crane hook to the aircraft        via the fitting; and    -   removing the fitting from the aircraft.

The first aspect of the invention recognises that a crane hook fittingpermanently mounted to the aircraft would be unacceptably heavy.Therefore the fitting is only secured to the aircraft for the liftingoperation, and removed afterwards. That is, the fitting is secured tothe aircraft when the aircraft is at a lifting location such as arunway, or an area adjacent to a runway (if the aircraft has overshot orveered to the side of the runway during a landing).

Typically the fitting has a first part configured to engage the cranehook; and a second part configured to engage a lowering device (whichmay also be a crane hook).

A second aspect of the invention provides a fitting for transmittinglifting loads from a crane hook to an item, the fitting comprising:

-   -   an attachment member configured to be secured to the item; and    -   a lifting member which is pivotally coupled to the attachment        member and configured to be engaged by the crane hook so as to        transmit lifting loads from the crane hook to the item.

The second aspect of the invention also provides a method of lifting anitem using such a fitting, the method comprising:

-   -   lowering the fitting into position with the lifting member        positioned below the attachment member;    -   securing the attachment member to the item;    -   lifting the lifting member by rotating it about its pivot until        it engages the item;    -   engaging the lifting member with a crane hook; and    -   transmitting lifting load from the crane hook to the item via        the lifting member.

The pivotal connection between the two parts of the fitting enables itto be secured in place without having to lift the whole fitting (whichmay weigh over 100 kg, and may be as much as 350 kg). Instead, thefitting is lowered into place, and only the lifting member needs to belifted by rotating about the pivot. By making the lifting membersufficiently light (preferably less than 100 kg) this operation can beperformed manually by one or two people.

Typically the attachment member and lifting member engage the samestrong point (that is, a reinforced region of the item) giving a compactarrangement.

The lifting member may engage the item in such a way that it cantransmit side loads to the item. However more preferably some or all ofthe side load from the crane hook is transmitted to the item via theattachment member.

Preferably the fitting is configured so that substantially no verticallifting load is transferred from the crane hook to the item via theattachment member. For example the pivotal connection may be pivotallycoupled to the attachment member by a floating connection.

The fitting may be used to lift any item, but is particularly suited toa method of lifting an aircraft.

A third aspect of the invention provides a crane hook assemblycomprising:

-   -   a hook having a centre of gravity;    -   an attachment link having a first pivot point attached to the        hook forward of its centre of gravity, and a second pivot point        configured to be lifted by a crane; and    -   a biasing system which applies a biasing force to the attachment        link causing the attachment link to rotate about the first pivot        point whereby the second pivot point moves towards the rear of        the hook when the hook is unloaded.

The third aspect of the invention also provides a method of lifting anitem using such a hook assembly, the method comprising:

-   -   coupling the hook to the item; and    -   applying a lifting force to the second pivot point of the        attachment link whereby the second pivot point rotates towards        the front of the hook against the biasing force.

The attachment link and associated biasing system ensure that the hookhangs substantially vertically when it is unloaded, making it easier tosecure in place.

The hook assembly may be used to lift any item, but is particularlysuited to a method of lifting an aircraft.

In its simplest form, the biasing system may consist of a biasing membersuch as a gas strut, or a tension or compression spring attached at oneend to the attachment link and at the other end to the hook. However aproblem with such an arrangement is that the biasing member must exert alarge biasing force. Therefore in a preferred embodiment the biasingsystem comprises a first biasing link coupled to the hook at a firstpivot point; a second biasing link coupled to the first biasing link ata second pivot point and to the attachment link at a third pivot point;and a biasing member which applies a biasing force causing the pivotpoints of the biasing links to move towards a co-linear configuration.Such a system employs mechanical advantage to reduce the force appliedby the biasing member. The biasing member may be for example a gas strutor a spring, attached to the hook or the attachment link.

A fourth aspect of the invention provides a crane hook comprising ashank portion; and a hook portion extending from the shank portion, thehook portion having a ball or socket configured to couple with a socketor ball on an item to be lifted.

The fourth aspect of the invention also provides a method of lifting anitem with such a hook, the method comprising:

-   -   forming a ball and socket joint by coupling the ball or socket        on the hook with the socket or ball on the item; and    -   applying lifting load to the item via the ball and socket joint.

In the preferred embodiment described below, the hook portion has a ballconfigured to couple with a socket in the item to be lifted. However inan alternative embodiment the hook portion may have a socket configuredto couple with a ball in the item to be lifted. In both cases, theresulting ball-and-socket joint enables relative rotation between theparts in any direction.

Preferably the ball or socket remains stationary with respect to thehook during use: thus it may either be a separate part which is fixed tothe hook, or it may be integrally formed with the hook.

The hook may be used to lift any item, but is particularly suited to amethod of lifting an aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 shows a main landing gear of an aircraft;

FIG. 2 shows a fitting in its inoperative position in which it islowered by a crane;

FIG. 3 is an exploded view of the crane fitting;

FIG. 4 is an isometric view of the side stay fitting and crane fittingtaken from below and the right hand side;

FIG. 5 is a first cross section through the side stay fitting and cranefitting;

FIG. 6 a is a second cross section through the side stay fitting andcrane fitting;

FIG. 6 b is a cross section through part of the side stay fitting andcrane fitting;

FIG. 7 a is an isometric view of the side stay fitting and crane fittingtaken from the front and left hand side;

FIG. 7 b is an isometric view of the underside of the crane fitting;

FIG. 8 is a side view of a crane hook assembly in its loaded state;

FIG. 9 is a side view showing part of the crane hook assembly in itsunloaded state;

FIG. 10 a is a view of the underside of the lifting pad;

FIG. 10 b is a sectional view taken along line B-B in FIG. 10 a, alsoshowing the ball retaining ring;

FIG. 10 c is a sectional view taken along line A-A in FIG. 10 a with theball and retaining ring in place; and

FIG. 11 is a view of the underside of a lifting pad with an alternativelocking plate.

DETAILED DESCRIPTION OF EMBODIMENT(S)

A main landing gear of an Airbus A340 aircraft is shown in FIG. 1. Thelanding gear comprises a main landing gear leg 2 which carries a wheelassembly 3. The main landing gear leg 2 is attached to the wingstructure, typically at a rear spar 8 and gear support rib 4 via a rearpintle-pin fitting 5. A side stay assembly 6 is pivotally attached tothe main landing gear leg 2 at one end, and to a side stay fitting 7 atits other end. The side stay fitting 7 is fitted to a rear spar 8 of awing.

In the event that the main landing gear 1 does not lower fully to itsdeployed position shown in FIG. 1 prior to landing, or fails duringlanding, then the aircraft will tilt to one side and that side of theaircraft will need lifting onto a support cradle.

Because the large structural components above the main landing gear leg2 are covered by an upper wing cover (not shown) it is not possible togain access to them to attach a sling. The side stay fitting 7 providesa strong point which is more accessible from above, but has no structurewhich can support a sling easily. Accordingly, the fitting 10 shown inFIGS. 2-7 is used to transmit lifting load from a crane hook to the sidestay fitting 7.

In a first step, an aperture is made in the upper skin (not shown) ofthe wing by removing access panels. Next, the side stay assembly 6(including a cardan pin 9 which couples it to the side stay fitting 7)is removed. Next, a crane lowers the fitting 10 through the aperturefrom above in the configuration shown in FIG. 2

The fitting 10 comprises an attachment assembly 11 which is configuredto be secured to the side stay fitting 7, and a lifting assembly 12which is pivotally coupled to the attachment assembly 11 and configuredto be engaged by a crane hook so as to transmit lifting loads from thecrane hook to the aircraft.

The attachment assembly 11 incorporates an eye pin 24 (shown in FIG. 3but omitted from all other figures) at its upper end which is used tolower the fitting in the configuration shown in FIG. 2 with the liftingassembly 12 hanging below the attachment assembly 11.

The various parts of the fitting 10 are shown in the exploded view ofFIG. 3.

The attachment assembly 11 comprises a vertical plate 20 with a hole 21bounded by a frame 22. A pair of lugs 23 extend from the lower edge ofthe vertical plate 20 (only one of the lugs 23 being visible in FIG. 3).A trunnion block 30, commonly referred to as a tombstone fitting, passesthrough the hole 21 in the vertical plate 20, with a tombstone flange 31engaging the frame 22. The tombstone 30 also passes through a hole 40 ina side clamping plate 41. The side clamping plate 41 has fourtrapezoidal blocks 42 which engage the side stay fitting 7 as shown mostclearly in FIG. 4. Pre-tensioning wedges 50 are received in slots 51 inthe rear face of the vertical plate 20. Wedge retention plates 52 areattached to the vertical plate 20 above the slots 51 as shown mostclearly in FIG. 5.

An eye pin 24 is screwed into a hole 25 in the upper edge of thevertical plate 20, and has an eye which is engaged by a conventionalcrane hook or lifting sling to lower the fitting into place. Note thatthe eye pin 24 and hole 25 are shown in FIG. 3 but omitted from allother figures.

The attachment assembly 11 is fitted to the side stay fitting 7 as shownmost clearly in FIGS. 6 a and 6 b. The side stay fitting 7 has a pair oflugs 62 which receive the cardan pin 9, and upper and lower flanges63,64 respectively. The fitting 10 is lowered by the crane hook untilthe tombstone 30 is aligned with the gap between the lugs 62 and flanges63,64. The tombstone 30 is then inserted into the gap into the positionshown in FIGS. 6 a and 6 b, and a dummy cardan pin 60 is inserted,securing the attachment assembly 11 to the lugs 62. The dummy cardan pin60 engages a dummy bush 61 and a pair of existing bushes 61 a,61 b asshown in FIG. 6 b. After the dummy cardan pin 60 has been fitted, thecrane hook supporting the fitting 10 is removed.

The clearance (indicated at 69 in FIG. 6 b) between the tombstone 30,the side stay lugs 62 and the flange of the bush 61 is kept to less than1.0 mm. This ensures the sliding motion along the dummy cardan pin 60 islimited to +/−0.5 mm.

As shown most clearly in FIG. 5, the trapezoidal blocks 42 engage theside stay lugs 62 at contact faces 65. The contact faces of the blocks42 may be covered with a protective layer to protect the sidestayfitting from damage. The protective layer may be, for example, a hardpolyurethane material or a soft metal such as brass or aluminium.

Because the side stay fitting 7 is handed, the blocks 42 are reversibleto enable the same fitting 10 to be used on either wing. The wedges 50between the vertical plate 20 and the side clamping plate 41 eliminatebacklash in the assembly at zero load. By adjusting screws 53 passingthrough the wedge clamp plates 52, the screws 53 force the wedges 50 in,to provide a light clamping of the tombstone 30 onto the dummy cardanpin 60 and the trapezoidal blocks 42 onto the sidestay fitting.

Returning to FIG. 3, the lifting assembly 12 will now be described. Themain component of the lifting assembly is a lifting pad 70, with threehinge lugs 71 at either end. Note that more or fewer lugs may beprovided if necessary. By having hinge lugs 71 at both ends, the liftingassembly 12 can be reversed relative to the attachment assembly 11 toenable the same fitting 10 to be used on either wing. The pair of hingelugs 23 on the vertical plate 20 are received in the slots between thehinge lugs 71, and a hinge pin 72 passes through the aligned holes inthe hinge lugs 71, 23. Trapezoidal blocks 73 are mounted on an upperface of the lifting pad 70. The contact faces of the blocks 73 may becovered with a protective layer to prevent damage to the aircraftstructure. The protective layer may be, for example, a hard polyurethanematerial or a soft metal such as brass or aluminium.

A hook socket member 74, hook retainer 75 and locking plate 76 aremounted on a lower face (not shown) of the lifting pad 70. The lockingplate 76 comprises a pair of slots 77 and a handle 78. The locking plateis slidably mounted to the bottom face of the lifting pad by a pair ofpins (not shown) extending downwardly from the bottom face of thelifting pad 70, and passing through the slots 77 of the locking plate76. The pins have nuts screwed onto their distal ends which prevent thelocking plate 76 from falling off. The locking plate 76 can be retractedto its release position shown in FIG. 2 in which it disengages thelifting assembly 12, allowing it to hang down in the configurationshown. After the attachment assembly has been fitted to the side staybracket 17, the lifting pad 70 is rotated about hinge pin 72 by 90° upto the operative position shown in FIG. 3 in which the blocks 73 engagethe underside of the lower flange 64 of the side stay fitting at acontact face 65 shown in FIG. 5. The weight of the lifting pad 70 isless than 100 kg to enable this to be achieved by two men. Thedownwardly directed contact face 65 of the side stay fitting 7 providesa suitably strong interface to transmit lifting loads without causingsignificant damage to the aircraft.

The lifting pad is then locked into its operative position by graspingthe handle 78 of the locking plate 76, and sliding it forward to thelocking position shown in FIG. 7 a. In the locking position, the lockingplate 76 engages both the vertical plate 20 and two of the hinge lugs 71of the lifting pad 70, preventing the lifting pad 70 from dropping backdown.

An alternative locking plate 76 b is shown in FIG. 11. The locking plate76 b has a handle 78 b and a pair of slots 77 b. The locking plate 76 bis operated in a similar manner to locking plate 76, although in thelocking position shown in FIG. 11 it engages the pad 70 between thehinge lugs 71, instead of engaging a pair of the hinge lugs 71.

The crane hook assembly 100 shown in FIGS. 8 and 9 is then lowered intoplace and engages a socket on the underside of the lifting pad as shownin FIGS. 10 a-10 c.

The hook assembly 100 includes a generally C-shaped hook with a verticalshank portion 102, a lifting portion 101 extending forwardly from anupper end of the shank portion; and a hook portion 103 extendingforwardly from a lower end of the shank portion. The shank portion 102is sufficiently long to accommodate the depth of the rear spar 8. Thehook portion 103 has an integrally formed ball 104 projecting upwardlyand positioned towards its distal end. The lifting portion 101 of thehook carries a pair of lifting mechanisms for ensuring that the hookwill always be in the vertical position when being lifted, i.e. eitherloaded or unloaded. The weight of the assembly 100 is approximately 1500Kg.

One of the two lifting mechanisms is attached to the left-hand side ofthe lifting portion 101 and is indicated at 105 in FIG. 8. The otherlifting mechanism is a mirror image of the lifting mechanism 105 and isattached to the right-hand side of the lifting portion 101 so is notvisible.

The lifting mechanism 105 comprises an attachment link 106 having afirst pivot pin 107 attached to the hook forward of its centre ofgravity 108, and a second pivot pin 109 which is coupled to theattachment link of the right-hand lifting mechanism (not shown). Thehook assembly is lifted by coupling a crane hook to the pin 109. Abiasing system applies a biasing force to the attachment link 106causing it to rotate about the first pivot pin 107 whereby the secondpivot pin 109 moves towards the rear of the hook to the position shownin FIG. 9 when the hook is unloaded.

The biasing system comprises a first biasing link 110 coupled to thehook via an arm 111 at the distal end of the upper lifting portion 103and a first pivot point 112; a second biasing link 113 coupled to thefirst biasing link 110 at a second pivot point 114 and to the attachmentlink 106 at a third pivot point 115; and a compression spring 116 whichapplies a biasing force causing the pivot points 112,114,115 to movetowards the approximately co-linear configuration shown in FIG. 9. Thebiasing system includes a mechanical stop (not shown) which prevents thepivot points 112,114,115 from moving to a fully co-linear configuration.

In the unloaded configuration shown in FIG. 9, the spring 116 pushes theattachment link 106 over by an angle of approximately 40 degrees so thatthe pivot pin 109 is above the hook's centre of gravity 108. Hence, asthe hook is lifted into position it will be in an upright position,enabling it to be easily coupled to the fitting 10. Then as the liftingload is applied, the lifting force applied to the second pivot pin 109of the attachment link 106 causes it to rotate towards the front of thehook against the biasing force of the spring. In the loaded positionshown in FIG. 8, the moment tending to push the attachment link 106 awayfrom the vertical is reduced to a low value, but sufficient to ensurethe link 106 rotates back to its unloaded position as the load on thehook approaches zero. The right-hand lifting mechanism (not shown) movestogether with the left-hand lifting mechanism 105 in a similar manner.

In an alternative embodiment (not shown) the spring 116 may be coupledat one end to the pivot point 114, and at its other end to the liftingportion 101 of the hook (instead of the attachment link 106).

As shown in FIG. 7 b, the underside of the lifting pad has a socketformed by the socket member 74 which is fitted into a recess in thelifting pad 70, and held in place by fasteners 82. Stiffening ribs 83extend radially from the socket member as shown in FIG. 7 b.

The ball 104 fits into the socket as shown in FIG. 10 c, with thesemi-spherical surface 104′ of the ball engaging the semi-sphericalsurface 84 of the socket. The ball 104 carries a retaining ring 86 shownin FIGS. 10 b and 10 c. After the ball has been inserted, the retainingring is secured in place by a pair of fastening studs which pass throughthe retaining ring 86 into holes 81 in the socket member shown in FIG. 7b. One of the fastening studs 87 is shown in FIG. 10 b. Thus theretaining ring 86 ensures that the ball 104 cannot drop out of thesocket if the crane cable goes slack. A consequence of this is that theretaining ring 86 and locking plate 76 must support the weight of thehook.

If the locking plate 76 is insufficiently strong to support the fullweight of the hook when the crane cable goes slack, then two alternativearrangements are possible:

-   -   the locking plate 76 may be omitted entirely, and the lifting        pad held in its operative position manually until the crane hook        is in place and carrying the weight of the lifting pad;    -   the retaining ring 86 may be omitted, and the socket in the        lifting pad made deeper to ensure that the ball 104 does not        slip out due to the action of side loads.

After the ball 104 has been secured in place, the hook 100 is lifted andthe lifting pad 70 transmits the vertical lifting load to the aircraftvia the side stay fitting 7 and spar 8. Once the aircraft is level, asupport cradle is placed under the wing, and the lifting load from thecrane is gradually reduced until the support cradle carries the fullweight. The fitting 10 is then engaged by the conventional crane hookwhich was previously used to lower it into place; removed from the sidestay fitting 7, and lifted away from the aircraft.

The ball and socket joint coupling the hook assembly 100 to the fitting10 can accommodate a relative rotation in any direction of 15 degrees.This accounts for the changing attitude of the aircraft as it is liftedand the probability that the slope of the contact surface of the lowerflange 64 is not horizontal when the aircraft is horizontal. Note thatin the case of the A340 the slope of the contact surface of the lowerflange 64 is 11 degrees when the aircraft is horizontal.

The holes in the hinge lugs 71 and/or the hinge lugs 23 are oval (withthe long axis of the oval aligned vertically). This provides a floatingconnection which enables the lifting pad 70 to float in the verticaldirection, ensuring that substantially none of the vertical liftingloads are transferred into the vertical plate 20. Therefore all of thevertical lifting load passes through the lifting pad 70 into the lowerflange 64 of the side stay fitting 7 and the rear spar of the wing.

Any side loads (i.e. fore-and-aft and transverse loads) arising from thelifting operation (typically due to the top of the crane jib slewingrelative to the aircraft, which may arise from the aircraft lurching asit lifts) will pass from the lifting pad 70 into the attachment assembly11, and then into the sidestay fitting 17. The hinge lugs 71, 23 aredesigned to accept a sideload of 33% of the vertical load, actingsimultaneously with the vertical load and acting in any direction.

Aluminium alloys can be used for some of the major components of thefitting 10, thus reducing its weight.

Clearances are minimised so as to prevent as far as possible anyslipping in the assembly. Pre-tensioning of the assembly using thewedges 50 removes backlash in the unloaded assembly.

Contact with the bottom wing skin (not shown) are restricted to areasimmediately below the side stay fitting 7 and the bottom flange and webof the rear spar 8.

It should be noted that although the fitting and crane hook assemblydescribed above are configured to lift an A340 aircraft via its sidestay fitting, the invention is not limited to such use. Therefore asimilar fitting and/or crane hook assembly may be used to lift the A340via another strong point, to lift another aircraft, or to lift any otheritem.

Although the invention has been described above with reference to one ormore preferred embodiments, it will be appreciated that various changesor modifications may be made without departing from the scope of theinvention as defined in the appended claims.

1. Apparatus for lifting an aircraft at a lifting location, theapparatus comprising: a fitting configured to be secured to the aircraftwhen the aircraft is at the lifting location; and a crane hookconfigured to engage the fitting and transmit lifting load to theaircraft via the fitting, the crane hook comprising a shank portion anda hook portion extending from the shank portion, wherein the fittingcomprises a socket or ball with a semi-spherical surface, and the hookportion comprises a ball or socket with a semi-spherical surfaceconfigured to engage the semi-spherical surface of the socket or ball onthe fitting and transmit lifting load to the aircraft via the fitting.2. The apparatus of claim 1 wherein the fitting has a first partconfigured to engage the crane hook; and a second part configured toengage a lowering device.
 3. The apparatus of claim 2 wherein the firstpart of the fitting is pivotally coupled to the second part of thefitting.
 4. A method of lifting an aircraft at a lifting location, themethod comprising: securing a fitting to the aircraft when the aircraftis at the lifting location; engaging the fitting with a crane hook;transmitting lifting load from the crane hook to the aircraft via thefitting; and removing the fitting from the aircraft, wherein the fittingcomprises a socket or ball with a semi-spherical surface, and the cranehook comprises a ball or socket with a semi-spherical surface whichengages the semi-spherical surface of the socket or ball on the fittingand transmits lifting load to the aircraft via the fitting.
 5. Themethod of claim 4 wherein the lifting load is transmitted to a spar of awing of the aircraft.
 6. The method of claim 5 wherein the lifting loadis transmitted to the spar by a side stay fitting of a main landinggear.
 7. The method of claim 4 further comprising lowering the fittinginto position with a lowering device.
 8. The apparatus of claim 1wherein the fitting comprises: an attachment member configured to besecured to the aircraft; and a lifting member which is pivotally coupledto the attachment member and configured to be engaged by the crane hookso as to transmit lifting loads from the crane hook to the aircraft. 9.The fitting of claim 8 further comprising a locking member which ismovable from a release position to a locking position in which thelocking member locks the lifting member in an operative positionrelative to the attachment member.
 10. The fitting of claim 8 whereinthe lifting member is reversible with respect to the attachment member.11. Apparatus for lifting an item, the apparatus comprising: a fittingaccording to claim 8, and a crane hook configured to engage the liftingmember so as to transmit lifting loads from the crane hook to thelifting member.
 12. A method of lifting an item, the method comprising:lowering the fitting of claim 8 into position with the lifting memberpositioned below the attachment member; securing the attachment memberto the item; lifting the lifting member by rotating it about its pivotuntil it engages the item; engaging the lifting member with a cranehook; and transmitting lifting load from the crane hook to the item viathe lifting member.
 13. The method of claim 12 further comprising:transmitting side load from the crane hook to the item via theattachment member.
 14. A crane hook assembly comprising: a hook having acentre of gravity; an attachment link having a first pivot pointattached to the hook forward of its centre of gravity, and a secondpivot point configured to be lifted by a crane; and a biasing systemwhich applies a biasing force to the attachment link causing theattachment link to rotate about the first pivot point whereby the secondpivot point moves towards the rear of the hook when the hook isunloaded, wherein the hook comprises a shank portion; and a hook portionextending from the shank portion, the hook portion having a ball orsocket configured to couple with a socket or ball on an item to belifted.
 15. The assembly of claim 14 wherein the biasing systemcomprises a first biasing link coupled to the hook at a first pivotpoint; a second biasing link coupled to the first biasing link at asecond pivot point and to the attachment link at a third pivot point;and a biasing member which applies a biasing force causing the pivotpoints of the biasing links to move towards a co-linear configuration.16.-17. (canceled)
 18. Apparatus for lifting an aircraft, the apparatuscomprising: the hook assembly of claim 14; and a fitting configured tobe secured to the aircraft and transmit lifting load from the crane hookto the aircraft.
 19. A method of lifting an item with the hook assemblyof claim 14, the method comprising: coupling the hook to the item; andapplying a lifting force to the second pivot point of the attachmentlink whereby the second pivot point rotates towards the front of thehook against the biasing force. 20.-22. (canceled)
 23. Apparatus forlifting an aircraft, the apparatus comprising: a crane hook comprising ashank portion; and a hook portion extending from the shank portion, thehook portion having a ball or socket configured to couple with a socketor ball on an item to be lifted; and a fitting configured to be securedto the aircraft and having a socket or ball configured to couple withthe ball or socket on the hook.
 24. A method of lifting an item with acrane hook comprising a shank portion; and a hook portion extending fromthe shank portion, the hook portion having a ball or socket, the methodcomprising: forming a ball and socket joint by coupling the ball orsocket on the hook with a socket or ball on the item; and applyinglifting load to the item via the ball and socket joint.
 25. (canceled)